Communication apparatus and communication method for EHT virtualization with multi-link devices

The present embodiments generally relate to communication apparatuses, and more particularly relate to methods and apparatuses for Extra High Throughput (EHT) virtualization for multi-link devices (MLDs).

In the standardization of next generation wireless local area network (WLAN), a new radio access technology having backward compatibilities with IEEE 802.11a/b/g/n/ac/ax technologies has been discussed in the IEEE 802.11 Working Group and is named 802.11be Extremely High Throughput (EHT) WLAN.

In IEEE 802.11be EHT WLAN, in order to provide better link adaptation and higher throughput over 802.11ax high efficiency (HE) WLAN, it is desired to increase the maximum channel bandwidth from 160 MHz to 320 MHz, increase the maximum number of space-time streams from 8 to 16, and support multi-link operation.

Further, in order to enable multi-link operations between an access point (AP) multi-link device (MLD) and a non-AP MLD, multi-link setup may be performed over one of the supported links to establish association for affiliated stations (STAs) in one or more links. Virtual APs (VAPs) may also be implemented.

However, there has been no discussion so far concerning EHT virtualization for MLD devices especially with regards to interconnections with Virtual LANs (VLANs).

There is thus a need for communication apparatuses and methods that can solve the above mentioned issue. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

Non-limiting and exemplary embodiments facilitate providing communication apparatuses and communication methods for EHT virtualization for MLD devices.

According to an aspect of the present disclosure, there is provided an Access Point (AP) included in a plurality of APs affiliated with an AP Multi-link Device (MLD), wherein each of the plurality of APs advertises a Basic Service Set Identifier (BSSID) and provides a link identified by a Link Identifier (ID), the AP comprising: circuitry, which in operation, generates a frame carrying a multi-link element containing information about the AP MLD and the plurality of APs; and a transmitter, which in operation, transmits the frame on a link, the Multi-link element indicating a Link ID of the link on which the frame is transmitted.

According to another aspect of the present disclosure, there is provided a non-AP Station (STA) included in a plurality of non-AP STAs affiliated with a non-AP MLD, the non-AP STA comprising: circuitry, which in operation, generates a Probe Request frame carrying a Multi-link element containing a MLD MAC Address of an AP MLD and one or more Link IDs of links affiliated with the AP MLD; and a transmitter, which in operation, transmits the Probe Request frame to request information about the AP MLD and the one or more links of the AP MLD.

According to another aspect of the present disclosure, there is provided a communication method comprising: generating a frame at an AP included in a plurality of APs affiliated with an AP MLD, wherein each of the plurality of APs advertises a BSSID and provides a link identified by a Link ID, the frame carrying a multi-link element containing information about the AP MLD and the plurality of APs; and transmitting the frame on a link, the Multi-link element indicating a Link ID of the link on which the frame is transmitted.

It should be noted that general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof. Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. The benefits and/or advantages may be individually obtained by the various embodiments and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and/or advantages.

Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been depicted to scale.

The following detailed description is merely exemplary in nature and is not intended to limit the embodiments or the application and uses of the embodiments. Furthermore, there is no intention to be bound by any theory presented in the preceding Background or this Detailed Description. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

VAPs enable a physical AP to act as two or more logical APs. Generally, all VAPs in a network operate on a same channel. BSSIDs (basic service set identifiers) corresponding to different VAPs typically have different settings (security, Quality of Service (QoS) etc.).

There are two main ways to implement VAPs:

A VLAN logically groups together two or more devices regardless of their physical presence in a wired network. VLAN allows devices on a same physical network to be partitioned into separate broadcast domains for simplicity, better security, traffic management, etc. Each VLAN is identified by a VLAN ID. One of the primary objectives for implementing a VLAN is to reduce broadcast traffic. The specification for VLAN is standardized by IEEE 802.1Q.

A common way to extend a VLAN to wireless LANs is to create a separate service set identifier (SSID) for each VLAN. It is also possible that more than one VLAN are mapped to a SSID. Each SSID is then mapped to a VAP (BSSID). Frames destined for different VLANs are transmitted by the VAPs wirelessly on different SSIDs, thus ensuring that only the clients associated with that VLAN receive those packets.

illustrates an example of how VLANs can be implemented. There are n VAPs in network, namely VAP-1, VAP-2up to VAP-n. BSSID-1corresponds to VAP-1, BSSID-2corresponds to VAP-2and BSSID-ncorresponds to VAP-n. There are also n VLANs in the network, namely VLAN1, VLAN2up to VLANn. For example, VLAN1is designated for staff and is mapped to SSID: Staff, VLAN2is designated for guests and is mapped to SSID: Guest, and VLANnis designated for IOT (Internet of Things) usage and is mapped to SSID: IOT. Each of these SSIDs is then mapped to a VAP. SSID: Staff is mapped to VAP-1(or BSSID-1), SSID: Guest is mapped to VAP-2(or BSSID-2) and SSID: IOT is mapped to VAP-n(or BSSID-n). Even though all the VAPs and non-AP STAs are operating on the same channel, only non-AP STA-1can receive packets transmitted by VAP-1, only non-AP STA-2can receive packets transmitted by VAP-1, and only non-AP STA-ncan receive packets transmitted by VAP-1.

Typically a VLAN is mapped to a SSID; in legacy systems, there is one to one mapping of BSSID and SSID, hence it is straightforward. For MLDs, however, mapping of SSIDs to BSSIDs is not clear as there can be multiple methods for doing so. Referring to an exemplary system as shown in, AP MLDcomprises of AP-1and AP-2. AP-1operates two virtual APs: VAP-1.1and VAP-1.2. This allows AP MLDhaving only two physical APs (AP-1and AP-2) to support 3 SSIDs (SSID: Staff, SSID: Guest and SSID: IOT) or VLANs (VLAN1, VLAN2and VLANn). However, in such deployments it is not possible to support non-AP MLDs since non-AP MLDs concurrently operate on multiple links, and could theoretically join multiple SSIDs but they should not be allowed to join multiple SSIDs at the same time due to security and other considerations.

To address the above-mentioned issues, the present disclosure proposes a two-tiered approach to implement virtualization using MLDs. Further, unified signalling that can support different virtualization architectures and usage is proposed to enable MLDs to quickly find information about other links of a peer link (for example, during Discovery, Multi-link setup etc.).

In a Tier 1 virtualization, the APs of an AP MLD are grouped into two or more AP groups to create multiple virtual AP MLDs from a single AP MLD. There is a single MLD MAC Address and a single MAC-SAP (medium access control— service access point) to the DS (distribution service). There can be 2 or more SSIDs per AP MLD and multiple virtual networks per AP MLD. Advantageously, Tier 1 virtualization is suitable for small deployments that only need few virtual networks, e.g. home networks or small businesses. The implementation is simple and there are less hardware requirements. SSID reconfigurations are also easier as there is no need to re-define MLDs.

In a Tier 2 virtualization, co-located APs are grouped into two or more AP groups to create multiple AP MLDs. There can be multiple MLD MAC-SAP to the DS and multiple MLD MAC Addresses, one per AP MLD. There is a single SSID per AP MLD and one AP MLD per virtual network. An advantage of Tier 2 virtualization is its suitability for large deployments that need more virtual networks, e.g. enterprise networks or big venues e.g. airports. However, implementation can be complicated and hardware requirements are higher as compared to Tier 1 virtualization.

depicts an illustration of an AP MLDimplementing a Tier 1 virtualization in accordance with various embodiments. AP MLDcomprises of AP-1, AP-2, AP-3& AP-4. AP-1& AP-2form the virtual AP MLD-1, while AP-3and AP-4form the virtual AP MLD-2. Further, virtual AP MLD-1is mapped to a SSID-1 while virtual AP MLD-2is mapped to a SSID-2. In other words, the APs of the AP MLDare grouped into two or more AP groups to create multiple virtual AP MLDs from a single AP MLD. Each group of APs is mapped to a unique SSID, such that all the APs of a virtual AP MLD advertise the same SSID, thus allowing 2 or more SSIDs per AP MLD. In this Tier-1 virtualization example, there is a single MLD MAC Address and a single MAC-SAP to the DS. Non-AP MLDs are only allowed to perform multi-link setup for links that are part of the same virtual AP MLD (i.e. same SSID). IDs may also be assigned to the virtual MLDs for easier identification purpose.

illustrate an implementation of a networkhaving Tier 1 virtualization only with physical APs in accordance with various embodiments. In networkof, 4 physical APs of AP MLDare divided into 2 groups. AP-1(corresponding to BSSID-1.1) and AP-2(corresponding to BSSID-1.2) advertise SSID: Staff. AP-3(corresponding to BSSID-2.2) and AP-4(corresponding to BSSID-2.1) advertise SSID: Guest. SSID: Staff is mapped to VLAN1while SSID: Guest is mapped to VLAN2. In other words, the AP MLDbridges wireless frames between the APs and the VLANs such that each SSID is mapped to a corresponding VLAN. Non-AP MLD-1is associated with SSID: Staff, while non-AP MLD-2is associated with SSID: Guest.shows an alternate view of the 4 APs. AP-1, AP-2, AP-3and AP-4operate on link 1, 2, 3 and 4 with Link IDs 1, 2, 3 and 4 respectively. A Link ID uniquely identifies the BSSID of an AP affiliated with an AP MLD. A Link ID is also associated with the Operating channel (i.e. Operating class and Channel number) associated with the BSSID, but the Link ID remains the same even if the operating channel changes. In this example, the wireless network represented by SSID Staff runs over Links 1 & 2, while the wireless network represented by SSID Guest runs over Links 3 & 4. An example of MAC addresses for the AP MLDand the 4 APs are shown below:

As a further analysis, the implementation of networkis equivalent to logically splitting an MLD into 2 virtual MLDs. During discovery, different APs can advertise different SSIDs. For Multi-link setup, the Non-AP MLD only requests to setup links belonging to SSID of interest. In terms of security, Group Keys (GTK/IGTK) are allowed to be different for different links, so there is no issue. Pairwise Keys (PTK) is same for all links, but there is also no issue since PTK is only for a single non-AP MLD. However all SSIDs will have the same security scheme (e.g. WPA-2). In some security associations, such as simultaneous authentication of equals (SAE), the SSID of a network and the corresponding password are used in the generation of the session specific Password Element of an ECC group (PWE). Specifically, the SSID and password is used to generate the pwd-seed, which in turn is used to generate the PWE:pwd-seed=HKDF-Extract(ssid,password[∥identifier])

Here, HKDF-Extract is the hash function as defined in IETF RFC 5869, and [∥identifier]) indicates the optional inclusion of a password identifier, if present. In such cases, although the security associations between different non-AP MLDs and AP MLD happen over the same MAC-SAP, different non-AP MLDs will use different SSID & password combinations to generate the PWE depending on which SSID the non-AP MLDs are joining. Since the PWE is used in the SAE commit messaged (during Authentication), in such cases the non-AP MLD or a non-AP STA also includes the SSID field in the Authentication frame so as to explicitly inform the AP MLD for which SSID it is requesting authentication. This is illustrated inin which the non-AP MLD indicates in the Authentication frametransmitted by the non-AP MLD to an AP MLD that it is requesting authentication for the network Staff by including the SSID fieldset to Staff in the Authentication frame. Since the AP MLD is made aware which SSID the non-AP MLDs are joining, there is no confusion at the AP MLD side on how to generate the PWE.

In regards to interconnection with VLANs, one VLAN ID is mapped to a SSID. The MLD needs to ensure that incoming frames (from DS) are sent to the correct SSID (BSSIDs) based on their VLAN ID, while correct VLAN IDs are attached to outgoing frames (to DS) based on SSID (BSSIDs) on which the frames are received. MLDs may also assign virtual MLD ID to each SSID (or VLAN) but there is just one MLD MAC address and one MAC SAP to DS. The constraint is that APs of a virtual MLD should not advertise different SSIDs. Otherwise, non-AP MLDs associated with the virtual MLD will receive frames from multiple VLANs. Thus, it is possible to segment an MLD to map to two or more VLANs. However, the number of VLANs that can be supported is low (Maximum number is only half the number of APs).

illustrate an implementation of a networkhaving Tier 1 virtualization without any interconnection to VLANs in accordance with various embodiments. In networkof, AP MLDprovides 2 virtual networks based on device types: one for regular MLDs, one for single-link MLDs and legacy STAs. 3 physical APs of AP MLDare divided into 2 groups. AP-1(corresponding to BSSID-1.1) and AP-2(corresponding to BSSID-1.2) advertise SSID: Multi-links and caters for Multi-link non-AP MLDs such as non-AP MLD-1. AP-3(corresponding to BSSID-2) advertise SSID: Single-link and caters to legacy STAs and Single Link MLDs i.e. MLDs that are capable of switching between multiple links but can only operate on one link at any given time, such as single link non-AP MLD-2. Non-AP MLD-1is associated with SSID: Multi-links while the single link non-AP MLD-2is associated with SSID: Single-link.shows an alternate view of the 3 APs. AP-1, AP-2and AP-3operate on links 1, 2 and 3 with Link IDs 1, 2 and 3 respectively.

illustrate an implementation of a networkhaving Tier 1 virtualization using a combination of physical APs and VAPs in accordance with various embodiments. In networkof, 1 Physical AP and 2 sets of VAPs of an MLD are divided into 3 SSIDs. AP MLDcomprises of AP-1, VAP-2, VAP-3& VAP-4. VAP-5is a standalone AP. AP-1(corresponding to BSSID-1) and VAP-2(corresponding to BSSID-2.1) advertise SSID: Staff; VAP-3(corresponding to BSSID-2.2) and VAP-4(corresponding to BSSID-3.1) advertise SSID: Guest. Standalone VAP-5(corresponding to BSSID-3.2) advertises SSID: IOT. SSID: Staff is mapped to VLAN1, SSID: Guest is mapped to VLAN2and SSID: IOT is mapped to VLAN3. In other words, the AP MLDbridges wireless frames between the APs and the VLANs such that each SSID is mapped to a corresponding VLAN. Non-AP MLD-1joins the network with SSID: Staff, non-AP MLD-2joins the network with SSID: Guest. STA-3joins the network with SSID: IOT.

VAP-2& VAP-3are virtual APs of the same AP and form a VAP Set 1. VAP-4& VAP-5are virtual APs of the same AP and form a VAP Set 2. Further, AP-1& VAP-2form a VAP MLD-1 (virtual AP MLD-1), while VAP-3and VAP-4form a VAP MLD-2. VAPs may be member of a co-hosted BSSID set or member of a Multiple BSSID set. In this example, the VAPs are implemented as Multiple BSSIDs. VAP-2& VAP-3are members of Multiple BSSID set 1 comprising BSSID-2.1and BSSID-2.2, while VAP-4& VAP-5are members of Multiple BSSID set 2 comprising BSSID-3.1and BSSID-3.2. In these Multiple BSSID sets, transmitting BSSIDs correspond to VAP-3and VAP-5; nontransmitting BSSIDs correspond to VAP-2and VAP-4. AP-1, VAP-3and VAP-5transmit Beacon frames. Even though multiple APs/VAPs may operate on the same link (frequency channel), different Link IDs may be assigned to the APs/VAPs.shows an alternate view of the 5 APs/VAPs. AP-1operates on link 3, VAP-2and VAP-3operate on link 2, while VAP-4and VAP-5operate on link 1. AP-1, VAP-2, VAP-3and VAP-5are assigned with Link IDs 1, 2, 3 and 4 respectively. An example of MAC addresses for the AP MLDand the 5 APs/VAPs are shown below:

As a further analysis, the implementation of networkis equivalent to logically expanding an MLD into 2 virtual MLDs & 1 standalone AP. During discovery, VAPs can advertise different SSIDs without any issues. For Multi-link setup, all APs of the MLD (including VAPs) advertise the same MLD address. However, different VAPs operate on different links (even though some of them operate on the same channel). In terms of security, different VAPs should have different Group Keys (GTK/IGTK). In regards to interconnection with VLANs, one VLAN ID is mapped to a SSID (and to a Virtual MLD). There is a single MLD MAC address and one MAC SAP to DS. Virtual MLD ID can be used for faster translation between VLAN IDs and SSIDs. The constraint is that APs of a virtual MLD should not advertise different SSIDs. Otherwise, non-AP MLDs associated with the virtual MLD will receive frames from multiple VLANs. Thus, it is possible to extend an MLD by using VAPs and map to two or more VLANs. However, the number of VLANs that can be supported is low, with the maximum number being the number of Physical APs. Another point to note for such deployment as shown in, is that since VAPs that belong to the same VAP set (either co-hosted BSSID set or Multiple BSSID set), are part of the same AP MLD, and since they cannot transmit and receive at the same time, special coordination is required between the virtual MLDs for multi-link transmission. For example, when AP1 604 and VAP2are engaged in a multi-link transmission with the non-AP MLD-1 in the Staff network, it is not possible for VAP3to also transmit at the same time due to the shared hardware resources with VAP2, and only VAP4can be used to transmit/receive frames to/from the non-AP MLD-2 in the Guest network.

Under Tier 1 virtualization, each SSID is mapped to 1 or more VLANs. When a VLAN tagged frame (for example, tagged with VLAN1) is received at a wired interface of an AP MLD, the AP MLD needs to ensure that the frame is only broadcasted on WLANs with SSID that is mapped to the VLAN whose ID is tagged in the received frame (for example, WLANs with SSID that is mapped to VLAN1). Similarly, when a frame destined to the DS is received on any of the wireless interfaces, based on the SSID, the AP MLD needs to ensure that the correct VLAN ID is tagged to the outgoing wired frame. In order to do so, the AP MLD needs to maintain a mapping of VLAN ID to SSIDs and AP MAC Addresses. An example of a mapping is shown in Table 1 below.

An example of a broadcasted 802.3 frameand 802.11 framebased on the mapping of Table 1 is shown in. 802.3 frameis transmitted from a router to an AP-MLD. 802.1Q header of the 802.3 frameindicates VLAN1 in VID field. As per Table 1, VLAN1 is mapped to SSID: Staff. Therefore, the resulting 802.11 framecan only be broadcasted by the APs that are mapped to the SSID corresponding to the VLAN ID in the received Ethernet frame i.e. in the 802.3 frame. In this example, the received broadcast Ethernet packet will be transmitted by AP1 or AP2 of SSID: Staff.

Since multiple SSIDs may share the same MAC-SAP in Tier 1 virtualization, the MA-UNITDATA.request primitive needs to indicate the destination SSID (or Virtual MLD ID instead if it exists), especially for broadcast data. An example of such a MAC data service primitive is shown below:

Based on the SSID field indicated in the MAC data service primitive, broadcast data frames are only transmitted on the BSSIDs corresponding to the indicated SSID. Alternatively, a list of BSSIDs can be provided instead of the SSID.

Tier 1 AP MLDs may be implemented as a shared Upper MAC (UMAC) structure without requiring complicated virtualization techniques like hypervisor.depicts an illustration of an AP MLDhaving Tier 1 virtualization with a shared UMAC structure in accordance with various embodiments. Shared UMACis responsible for ensuring the correct translation of wired VLAN frames to and from wireless frames. The constituent APs (AP-1, AP-2, AP-3and AP-4) are tightly coupled together, so sharing of information is easier, but performance may be affected by the sharing of common resources (e.g. memory etc.).

Under Tier 2 virtualization, co-located APs are grouped into two or more AP groups to create multiple AP MLDs.depicts an illustration of co-located APs that are grouped into two or more AP groups to create multiple AP MLDs for a Tier 2 virtualization in accordance with various embodiments. In this illustration, co-located APs (AP1 902, AP2 904 and AP3 906) are used to create AP MLD1, AP MLD2and VAP. Each AP MLD is mapped to a unique SSID. Each SSID is mapped to 1 or more VLANs. There are multiple MAC-SAPs to the DS and multiple MAC Addresses, one per AP MLD or VAP. By using VAPs (up to 8 per physical AP), many MLDs can be created to support a large number of VLANs. Since the APs/VAPs may be affiliated with different AP MLDs, the link IDs can be assigned in two ways:

illustrate an implementation of a networkhaving Tier 2 virtualization with multiple AP MLDs in accordance with various embodiments. 3 sets of VAPs are mapped to 2 MLDs and 3 SSIDs. AP MLD1comprises of VAP-1(corresponding to BSSID-1.1), VAP-3(corresponding to BSSID-1.2) and VAP-5(corresponding to BSSID-1.3), and advertises SSID: Staff. AP MLD2comprises of VAP-2(corresponding to BSSID-2.1) and VAP-4(corresponding to BSSID-2.2), and advertises SSID: Guest. Standalone VAP-6corresponds to BSSID-3and advertises SSID: IOT. Non-AP MLD-1is associated with SSID: Staff, non-AP MLD-2is associated with SSID: Guest and STA-3is associated with SSID: IOT. In this example, the VAPs may be co-hosted BSSIDs or Multiple BSSIDs. When the VAPs are members of Multiple BSSID set, transmitting BSSIDs correspond to VAP-1, VAP-4and VAP-6such that each virtual network has at least one Beacon frame; accordingly, VAP-1, VAP-4and VAP-6transmit Beacon frames.

shows an alternate view of the APs/VAPs. VAP-1and VAP-2operate on link 3, VAP-3and VAP-4operate on link 2, while VAP-5and VAP-6operate on link 1. Since the VAPs are affiliated with different AP MLDs, the link IDs can be assigned in two ways. In a first way, Link IDs are local to an AP MLD. e.g. VAP-1, VAP-3& VAP-5are assigned Link IDs 1, 2 and 3 respectively by AP MLD1, while VAP-2and VAP-4are assigned Link IDs 1 and 2 by AP MLD2. In a second way, Link IDs are assigned globally for co-located MLDs. E.g. VAPs 1-5 are assigned Link IDs 1-5 respectively. An example of MAC addresses for the MLDs and the 6 VAPs are shown below:

As a further analysis, the implementation of networkis equivalent to expanding groups of co-located physical APs into multiple MLDs using VAPs. During discovery, when the number of MLDs is greater than the number of Physical APs, Multiple BSSID approach will have an issue of advertising MLD information (e.g. MLD MAC address). There may also be issues in MLD MAC address assignment and signaling efficiency. For Multi-link setup, non-AP MLDs should be able to easily discover the APs or VAPs on the other links of a MLD, especially if the VAPs are Nontransmitted BSSIDs. In terms of security, different VAPs should have different Group Keys (GTK/IGTK). In regards to interconnection with VLANs, one VLAN ID is mapped to a SSID (and to a Virtual MLD). There are multiple MLD MAC addresses and multiple MAC SAPs to the DS. If a single SSID is mapped to a single MLD, a VLAN ID can be mapped to a MLD MAC Address. But a single MLD MAC address would be more appropriate if there is only 1 physical connection to the DS. Thus, using VAPs, MLDs can be virtualized to support multiple VLANs.

illustrate an implementation of a networkhaving Tier 2 virtualization using multiple AP MLDs with only physical APs in accordance with various embodiments. Referring to, 2 sets of VAPs mapped to 2 MLDs and 2 SSIDs. AP MLD1comprises of VAP-1and VAP-2, and advertises SSID: Staff. AP MLD2 comprises of VAP-3and VAP-4, advertises SSID: Guest. Non-AP MLD-1is associated with SSID: Staff, while non-AP MLD-2is associated with SSID: Guest.shows an alternate view of the VAPs. VAPs 1-4 operate on links 1-4 respectively. Since the VAPs are affiliated with different AP MLDs, the Link IDs can be assigned in two ways. In a first way, Link IDs are local to an AP MLD. For example, VAP-1and VAP-2are assigned Link IDs 1 and 2 respectively by AP MLD1, while VAP-3and VAP-4are also assigned Link IDs 1 and 2 by AP MLD2. In a second way, Link IDs are assigned globally for co-located MLDs. For example, VAPs 1-4 are assigned Link IDs 1-4 respectively.

Under Tier 2 virtualization, each SSID is mapped to 1 or more VLANs. When a VLAN tagged frame is received at a wired interface of an AP MLD, the AP MLD needs to ensure that the frame is only broadcasted on WLANs with SSID that is mapped to the VLAN ID tagged in the received frame. Similarly, when a frame destined to the DS is received on any of the wireless interfaces, based on the SSID, the AP MLD needs to ensure that the correct VLAN ID is tagged to the outgoing wired frame. Further, the AP MLD needs to maintain a mapping of VLAN ID to SSIDs and MLD/AP MAC Addresses. A mapping based on the networkis shown in Table 2 below:

Further, an example of an 802.11 frameand 802.3 framebased on the mapping of Table 2 is shown in. The 802.11 frames are only broadcasted by the APs affiliated with the AP MLD that is mapped to the SSID corresponding to the VLAN ID in the received ethernet frames. In this example, the broadcast 802.11 packets received by VAP-3& VAP-4of SSID: Guest will be tagged with IEEE 802.1Q tag with VLAN ID=VLAN2 (as shown in VID fieldof 802.3 frame) before forwarding to the Ethernet interface.

When only physical APs are involved or only a few VAPs are involved, Tier 2 AP MLDs may also be implemented without using hypervisor virtualization.depicts an illustrationof Tier 2 AP MLD1and AP MLD2without hypervisor virtualization in accordance with various embodiments. AP MLD1comprises an AP-1and AP-2, while AP MLD2comprises an AP-3and AP-4. In this implementation, each AP MLD1and AP MLD2behaves as a distinct entity, with its own MAC-SAP to the DS. Advantageously, translation of VLAN frames and wireless frames is simple due to the one-to-one mapping between AP MLDs and VLANs.

When many VAPs are involved, Tier 2 AP MLDs may need to be implemented using hypervisor virtualization.depicts an illustrationof Tier 2 AP MLD1, AP MLD2and VAP-6with hypervisor virtualization in accordance with various embodiments. AP MLD1comprises VAP-1, VAP-3and VAP-5, while AP MLD2comprises VAP-2and VAP-4. Virtualization layeris responsible for ensuring the correct binding of the virtual APs with physical APs AP-1, AP-2and AP-3. Each AP MLD1, AP MLD2and VAP-6behaves as a distinct entity, with its own MAC-SAP to the DS. Advantageously, translation of VLAN frames and wireless frames is simple due to the one-to-one mapping between AP MLDs and VLANs.

Unified signaling that can support different architectures & different usages is proposed.depicts an illustration of a Multi-link elementconfigured for unified signalling in accordance with various embodiments. The Multi-link elementcomprises an Element ID field, a Length field, an Element ID extension field, a Type field, a Common Information fieldand one or more Per-link information field. Type fieldis set to Discovery when used by an AP MLD to advertise link information, or set to Multi-link Setup when used by a non-AP MLD during Multi-link Setup. An example of various Type field values that can be implemented are shown in Table 3 below:

Common Information fieldcomprises a Common Control field, a Host Link ID field, a MLD MAC Address field, Multi-link Capabilities field and a SSID field. The Common Control fieldcomprises a Host Link ID Present field, MLD MAC Address Present field, Multi-link Capabilities Present field, SSID Present field and Number of Per-link Information field. The Number of Per-link Information fieldindicates how many Per-link Information fields are present.indicates none. The Common Information fieldcarries information about the MLD that is common across all links e.g. MLD MAC Address, Multi-link capabilities, common SSID etc. The Host Link ID fieldindicates a Link ID assigned to the link in which the Multi-link elementis transmitted (i.e. host link). If all the links of an AP MLD advertise the same SSID, MLD level SSID may be defined and indicated in the Common Information field and the SSID fields are omitted in the per-link info. Fields. In such cases, the beacon frame carries the SSID for legacy devices, which may be different from the MLD level SSID defined for non-AP MLDs.

The Per-link information fieldcomprises a Presence Bitmap field, a Link ID field, a Capability Information field, a Listen Interval field, an AID field, SSID field, BSSID/MAC Address field, a Nontransmitted BSSID Information field, an Operating Channel fieldand zero or more Optional Subelements field. The Presence Bitmap fieldcomprises a Capability Information Present field, a Listen Interval Present field, a SSID present field, a BSSID/MAC Address Present field, a Nontransmitted BSSID Info. Present field and an Operating Channel Present field etc. The Nontransmitted BSSID Information comprises a Transmitted BSSID field, a MaxBSSID Indicator fieldand a BSSID Index field. The Operating Channel fieldcomprises an Operating Class field and a Channel Number field. When present, each Per-link Information fields represents one of the links of the MLD; typically information of the host link (the link on which the frame carrying the Multi-link element is transmitted on, or the link on which the AP/VAP associated with the Multi-link element operates on) is not carried in the Per-link Information field. If a link corresponds to a Nontransmitted BSSID, the Nontransmitted BSSID Information fieldprovides identity of the transmitted BSSID. Other subelements related to the link, e.g. EHT Operation element, EDCA (Enhanced Distributed Channel Access) Parameter Set element etc. may be carried if different from the information of the host link.

As a variation, the Common control field may also be placed outside the Common Information field right after the Type field, or it may even replace the Type field. The Common control field in such case can also indicate whether the ML element carries the Common Information field, or the per-link information fields. Instead of fields, each Per-link information may also be a sub-element. Also, instead of the full SSID, a 4-octer long short/compressed SSID (32-bit CRC calculated over the SSID) may also be used in the Common Information field as well as the Per-link information fields. The Multi-Link element may also carry a non-inheritance element to indicate which element carried in the host frame is not inherited by the link information. The concept of non-inheritance can be useful when a reported link/AP doesn't inherit certain element. For example, if the reporting AP (i.e. the AP corresponding to the host link/element) supports UORA (UL OFDMA-based Random Access) while the reporting AP's (APs corresponding to the per-link information) does not support UORA, then the non-inheritance element signals this information—i.e., not inheriting UORA.